1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device having a photosensor to which information is input by light radiation.
2. Description of the Related Art
There is known a photosensor to which image information is input by light radiation. Photosensors include semiconductor photovoltaic elements such as photodiodes and phototransistors, and photoconductive elements having a resistance variable due to light radiation. A CCD (Charge-Coupled Device) is well known as a charge transfer system having functions of photoelectric conversion, charge-accumulation and scan. Although the CCD is capable of transferring charge without a switching element, it is necessary to use a semiconductor substrate. Thus, the CCD cannot be formed on an insulating substrate such as a glass substrate.
On the other hand, an active matrix-type LCD device is known as a display device. In this display device, a liquid crystal is sealed between a pair of glass substrates. One of the glass substrates is provided with a plurality of data lines and a plurality of access lines. The data lines intersect the access lines at right angles. Each intersection of these lines is provided with a pixel electrode and a non-linear active element for connecting the associated data line and access line.
As stated above, there are conventionally known an image input device and an image display device, each of which is constituted as an individual element. If these individual devices are used to manufacture an electronic apparatus having input and display functions, the size of the apparatus becomes large and the portability of the apparatus deteriorates. Since each device has a switching element associated with each photodetector or each display electrode, the electronic apparatus having input/output functions must have double the number of switching elements, and the manufacturing cost increases.